The invention relates to a device for recognizing a predetermined pulse pattern from a pulse stream. The device comprises delay elements which are chosen so that the delay of a delay element associated with a pulse from the pulse pattern to be recognized corresponds to the relative time distance between the pulse to be delayed and the last pulse of the pulse pattern. The delay elements are each connected at an input end, in parallel, to one end of a conductor for transporting the pulse stream to the delay elements. The device further comprises a coincidence element for detecting time coincident pulses at the output ends of the delay elements.
A device of this kind is known from German Pat. No. 885,102. Due to the specific choice of the delay of the delay elements and the fact that they are connected in parallel to the conductor for transporting the pulse stream, the various pulses of the pulse pattern are simultaneously presented to the output ends of the delay elements. The coincidence element, which is in this case connected to the output ends of delay elements, detects these time coincident pulses, so that the pulse pattern can be recognized. This pulse pattern can be used, for example, for synchronizing a receiver and a transmitter.
A major drawback of the above-described device is its susceptibility to faults. Because the pulses are presented directly to the coincidence element, an interference pulse which is present in the direct vicinity of a pulse of the pulse pattern may be strong enough to trigger the coincidence element. The accuracy of such a device may then be insufficient, notably for processing fast signals.